International Journal of Latest Research in Engineering and Technology (IJLRET) ISSN: 2454-5031 www.ijlret.comǁ Volume 2 Issue 3ǁ March 2016 ǁ PP 69-76 EXPERIMENTAL STUDY ON PARTIAL REPLACEMENT OF COARSE AGGREGATE BY SEASHELL & PARTIAL REPLACEMENT OF CEMENT BY FLYASH R. Yamuna Bharathi1, S. Subhashini2, T. Manvitha3, S. Herald Lessly4 1, 2&3Undergraduate student, Department of Civil Engineering, R.M.K.Engineering College, TamilNadu, India. 4Assistant Professor, Department of Civil Engineering, R.M.K.Engineering College, TamilNadu, India. ABSTRACT:The growing concern of resource depletion and global pollution has lead to the development of new materials relying on renewable resources. Many by- products are used as aggregate for concrete. Seashell waste which is a major financial and operational burden on the shellfish industry is used as an ingredient in concrete thus offering alternatives to preserve natural coarse aggregate for future generation. Seashell is mainly composed of calcium and the rough texture make it suitable to be used as partial coarse aggregate replacement which provides an economic alternative to the conventional materials such as gravel. Experimental studies were performed on conventional concrete and mixtures of seashell with concrete. The percentage of seashell, is varied from 3% to 11%. Also the cement is replaced for 25% of flyash. The mechanical properties of concrete such as compressive strength, tensile strength, flexural strength, and workability are evaluated. This research helps to access the behaviour of concrete mixed with seashell and determination of optimum percentage of combined mixture which can be recommended as suitable alternative construction material in low cost housing delivery especially in coastal areas and near fresh water where they are found as waste. KEY WORDS:Seashell, compressive strength, tensile strength, flexural strength, workability, coastal areas. I. INTRODUCTION Civil engineering practice and construction works in India depend to a very large extent on concrete. Concrete is one of the major building materials that can be delivered to the job site in a plastic state and can be moulded insitu or precast to virtually any form or shape. Concrete basic constituents are cement, fine aggregate (sand), coarse aggregate (granite chippings) and water. Hence, the overall cost of concrete production depends largely on the availability of the constituents (and selected additives). Water reacts chemically with cement to form the cement paste, acts as binder holding the aggregate together which is an exothermic hydration reaction. Aggregates are usually described as inert "filler" material of either the fine (sand) or coarse (gravel) variety. It tends to represent a relatively high volume percentage of concrete, to minimize costs of the material. In present generation as the population is increasing rapidly along with the increase in construction work, to replace the old process, the new bricks like fly ash bricks came into field replacing the old lime bricks, whereas the cementing material like mud, lime paste and gums is replaced by the cement of different kinds in different construction. The continuously growing construction industry has posed the possibility on depletion of natural aggregates in the future that would increase the cost of concrete material. So the need for replacement of present aggregates is a growing concern to meet the demand for aggregates in the structures. Thus alternative options are adopted for non-load bearing walls and non-structural floors in buildings. Recent studies focuses on the locally available waste to be used as aggregates. One such waste is the seashells obtained from coastal areas, freshwater lakes, and riverine areas. Seashell is a hard, protective layer, a calcareous exoskeleton which encloses, supports and protects the soft parts of an animal (molluscs). As they grow, the shells increases in size which becomes a strong compact casing for the mollusc inside. The major molluscan seashell includes, bivalves such as clams, scallops, and cockle. The hard shells are regarded as waste, which are accumulated in many parts of the country, when dumped and left untreated may cause unpleasant odour and disturbing view to the surrounding. Also the aggregate surface texture influences the bond between aggregate and cement paste in hardened concrete. Thus it opens an investigation into its potential as a partial replacement of coarse aggregate. II. LITERATURE REVIEW Many researchers have studied the engineering properties of sea shell, crushed sea shell aggregates and seashell ash in the recent past. A. P. Adewuyi and T. Adegoke et al (2008) concluded that the strength of periwinkle shell concrete is determined based on the properties of the shells and various percentage replacements; Concrete with 35.4% and www.ijlret.com 69 | Page EXPERIMENTAL STUDY ON PARTIAL REPLACEMENT OF COARSE AGGREGATE BY SEASHELL & PARTIAL REPLACEMENT OF CEMENT BY FLYASH 42.5% periwinkle shells inclusion can still give the minimum 28-day cube strength values of 21 N/mm2 and 15 N/mm2 expected for concrete mixes 1:2:4 and 1:3:6, respectively. Osarenmwinda et al (2009) investigated the potential of periwinkle shell as coarse aggregate for concrete. The results showed that concretes produced with ratio (1:1:2, 1:2:3 and 1:2:4) mixes indicated compressive strengths of 25.67 N/mm2, 19.5 N/mm2 and 19.83 N/mm2 at 28 days curing age respectively. These strength values met the ASTM-77 recommended minimum strength of 17 N/mm2 for structural light weight concrete while the mixes with compressive strengths of 14 N/mm2 and 16.5 N/mm2 respectively did not meet the standard values. Falade, Ikponmwosa and Ojediran (2010) investigated the behaviour of lightweight concrete containing periwinkle shells at elevated temperature and found that the compressive strength decreased with increase in water/cement ratio and temperature. Festus, Oriyomi Olatunji (2012) conducted experiments to assess the suitability of periwinkle shell ash as partial replacement for Ordinary Portland cement and found that that the crushing strength decreases as the percentage of Periwinkle Shell Ash (PSA) increases and the crushing strength increases as the age of curing increases for each of the percentage replacement. Also the initial and final setting time of the OPC/PSA mixes (at 5% and 10%) was found to increase with increasing replacement, this means that PSA concrete is not susceptible to the problem of flash and false set .O.Ettu, O. M. Ibearugbulem, J. C. Ezeh, and U. C. Anya et al(2013) concluded that the density of the concrete decreased with increase in the percentage of periwinkle shells, from 2466.67 Kg/m for 25% periwinkle shell replacement at a mix ratio of 1: 1.5: 3 to 2103.33 Kg/m3 for 75% periwinkle shell replacement at a mix ratio of 1: 2.5: 3. Values of 28-day compressive strength ranged from 24.15 N/mm2 for 75% periwinkle shell replacement to 33.63 N/mm2 at 25% replacement. Most of these values hardly satisfy the minimum 25 N/mm2 requirement. Gurikini Lalitha, C. Krishna Raju (2014) studied the performance of M30 concrete with partial replacement of seashells and coconut shells. They found that the compressive strength of the concrete cubes has gradually decreased from addition of 10% (5% + 5%) of coconut shells and sea shells. Whereas comparing to traditional concrete, compressive strength of 10% (5% + 5%) of coconut shells (5%) and sea shells (5%) increased. It can be observed that very few experimental studies have been reported in the literature. Hence, a detailed experimental investigation has been carried out on mechanical properties of concrete by varying the percentages of seashell. Recommendations on the optimum seashell content as a coarse aggregate is made based upon experimental results. The present proposed study is expected to produce results to enhance the understanding of the seashell as a coarse aggregate in concrete along with partial replacement of cement by flyash of 25%. Further it was planned to extend the studies into workability characteristics while using seashell as partial replacement. This can be effectively used for the improved concrete construction with local materials. III. OBJECTIVE AND SCOPE The objective of the research proposal is to study the influence of percentage of seashell as partial replacement of coarse aggregate and percentage of flyash as partial replacement of cement on mechanical properties of concrete to establish the optimum percentage of seashell and flyash, for the chosen size and type of seashell aggregate especially in coastal and riverine areas. The detailed scope of the study is summarized as below: Conducting experimental studies of mechanical properties of seashell coarse aggregate. Experimenting the concrete mixes containing 0%, 3%, 5%, 7%, 9% and 11% of seashell as partial replacement of coarse aggregate along with partial replacement of cement by fly ash of about 25%, to evaluate the mechanical properties of concrete such as compressive strength, tensile splitting strength, and flexural strength characteristics. Analysing and studying the effect of varying percentages of seashell and fly ash and comparing the results with normal concrete without any replacements. Performing the slump test and analyzing the variation of slump for different percentages of seashell to obtain the workability characteristics of the concrete with partially replaced seashell as coarse aggregate. Obtaining the optimum percentage of seashells and flyash based upon the test results. IV. MATERIALS 4.1 Cement The most common cement used is Ordinary Portland Cement (OPC).The OPC is of 53 grade confirming to IS: 12269-1987 is been used. The properties of the cement are specific gravity of 2.89, normal consistency of 28%, initial and final setting time of 27 min and 535 min respectively. www.ijlret.com 70 | Page EXPERIMENTAL STUDY ON PARTIAL REPLACEMENT OF COARSE AGGREGATE BY SEASHELL & PARTIAL REPLACEMENT OF CEMENT BY FLYASH 4.2 Fine Aggregate The sieve analysis for fine aggregate expressed a fineness modulus of 2.36.